Ya...they have gone bad. The SRS light goes on (which can be many diff. things) and when they check the code I guess they determine it's the pretensioner as a part of the SRS system. I know if the SRS light goes on, the air bags can't deploy, so its important to keep the system running properly. I've looked on the internet a good bit and there doesn't seem to be a problem with DiscoII 2001. I have read though that most times when a pretensioner is creating an error code in the srs system, it is the connection under the seat. I read the connection can be cleaned (I believe they said spray/ clean with wd40). Then reset. I'm not a mechanic or anything, but I really like to atleast know the systems of my car so I know when a mechanic is blowing smoke.